The present invention relates to inspecting the quality of moving images such as videos or motion pictures. More particularly, the present invention relates to a method and apparatus for detecting a shot of short time duration inserted in a moving image stored on video tape or a video disc, and displaying a representative image of the shot of short time duration.
Due to the popularity of satellite broadcasting, cable television and the like, in addition to existing television broadcasting, the number of broadcasting channels have steadily increased. If a wide-band communications infrastructure called an xe2x80x9cInformation Highwayxe2x80x9d is established in the future, broadcasting will be easy to carry out. Thus, far more industrialists will take part in the broadcasting industry than do today further accelerating the increase in the number of broadcasting channels. With such a large amount of information being broadcasted it is possible that some of the information may contain illegal images which are intended to manipulate people. For example, there is a known phenomena called xe2x80x9cSubliminal Suggestionxe2x80x9d which is intended for illegal psychological manipulation of an audience. Subliminal suggestion is accomplished by inserting special images of extremely short time duration into a moving image. It is thought that subliminal suggestion is capable of subconsciously influencing an audience to perform a suggested act without the audience being aware that such a suggestion has occurred. For this reason, it is necessary to determine whether each program to be broadcast contains subliminal suggestion information and prevent broadcasting of such program. However, according to conventional technology, it is necessary to manually inspect a moving image while feeding it on a frame-by-frame basis. Thus, even if the moving image can be inspected at a rate of one frame per second, at least 48 hours would be required to inspect an entire 2-hour motion picture. As a result, it is physically impossible to inspect every program to be broadcast.
An object of the present invention is to provide a method and apparatus for detecting a shot of short time duration inserted in a moving image stored on video tape or a video disc and displaying a representation image of the shot.
To achieve the above object, the present invention provides input apparatus for inputting a moving image as a target sequentially in time on a frame-by-frame basis (one frame is one still image which constitutes part of a moving image, and generally televisions are arranged to display 30 frames per second), a shot change point detector for sequentially detecting from the moving image a plurality of shot change points representing points between a pair of frames where images of a preceding shot and images of a succeeding shot have changed, a shot duration detector for detecting a time duration of a shot between a time of a preceding shot change point (hereinafter referred to as the first time instant) and a time of a succeeding shot change point (hereinafter referred to as the second time instant), and apparatus for displaying a representative image of the shot and the time duration of the shot, if the duration time of the shot between the first and second time instants is shorter than a set time period. The time of occurrence of the shot can also be displayed with the representative image and time duration thereof.
There are also provided apparatus for displaying the representative image in the form of a list and apparatus for displaying the list so as to be indicative of the time duration of the shot corresponding to the representative image. Thus, the time duration of the shot represented by the representative image can be easily checked by viewing.
Further provided is apparatus for storing the first or any one,of the frames of the shot as the representative image when the duration of the shot is being detected by the shot duration detector. The stored frame may be later retrieved as the representative image when the duration of the shot is shorter than the set time, period. Also provided is apparatus for reducing the stored frame, retrieving the reduced frame as the representative image when the duration of the shot is shorter then the set time, and displaying the reduced frame as an icon representative of the shot of short time duration.
According to the present invention, it is possible to automatically detect a shot of short time duration without relying on human labor, thereby making it possible to automatically detect a picture portion in which an illegal image may be inserted. Since it is similarly possible to detect a meaningless shot of short duration which has been erroneously inserted during editing, it is also possible to improve the quality control of broadcast programs by detecting low quality short duration frames and deleting them the same as illegal images.
In the present invention the number of detected shots of short time duration to be inspected by a user can be reduced according to two conditions. The first condition is whether a plurality of shots of short duration have been successively detected at intervals of a duration shorter than a specified duration. The second condition is whether a shot of short time duration has been detected within a short period of time after detection of a previous shot of short time duration and whether the image of the detected shot of short time duration is similar to the image of the previously detected shot of short time duration.
If the first condition is satisfied all of the detected shots of short time duration are grouped together in a group with a single representative image. If the second condition is satisfied the detected shot of short time duration is added to the group containing the previously detected shot of short time duration.
In the present invention a representative image of a group of detected shots of short time duration is displayed in such a manner to indicate that it represents a group of detected shots of short time duration. Selection by the user of such a representative image causes the hierarchical display of the representative image of the group and representative images of all of the detected shots of short time duration that make up the group. Selection of any of the representative images of the detected shots of short time duration that make up the group allows the user to individually inspect the images of the detected shots of short time duration that make up the group.
Thus, by use of the present invention since representative images corresponding to a detected doubtful picture portion which may be illegal are displayed in the form of a list, the detected doubtful picture portion can readily be checked. If there is an error in the picture portion, the user can quickly check the picture portion while viewing it with his/her own eyes.
Further, since time information indicating the duration and when such a picture portion was detected is also displayed together with the corresponding representative image, it is possible to readily know not only the position of the picture portion in the entire picture but also the time duration of the picture portion, variations in the distribution of the picture portion with time, and the like.